1. Field of the Invention
The present invention relates to a head slider for use in disk apparatuses, and a method of manufacturing such a head slider.
2. Description of the Related Art
In recent years, there have been demands for smaller and larger-capacity magnetic disk apparatuses as one type of external storage device for use with computers. One proposal for increasing the storage capacity of magnetic disk apparatuses is to increase the number of magnetic disks mounted on a spindle motor. Based on the proposal, recently available magnetic disk apparatuses have disks that are installed at smaller spaced intervals. Magnetic disk apparatuses that are available today often employ a contact-start-stop (CSS) floating magnetic head slider. When the magnetic disk apparatus is stopped, the CSS floating magnetic head slider is held in contact with a magnetic disk. When the magnetic disk apparatus operates to record or reproduce information, the CSS floating magnetic head slider floats off the surface of a magnetic disk by a minute gap therebetween due to an airflow that is produced on the surface of the magnetic disk that is rotating at a high speed.
The CSS floating magnetic head slider incorporates an electromagnetic transducer (magnetic head element) that is subject to the airflow that is produced on the surface of the magnetic disk. The magnetic head slider is supported by a suspension. When the magnetic disk is not rotating, the magnetic head slider that incorporates the electromagnetic transducer therein is held against the surface of the magnetic disk. When the magnetic disk is rotating, the magnetic head slider flows off the magnetic disk due to the airflow that is produced by the rotation of the magnetic disk and acts on a floating surface of the magnetic head slider. The electromagnetic transducer incorporated in the magnetic head slider moves over the surface of the magnetic disk while being supported by the suspension, and records information on and reproduces information from tracks on the magnetic disk.
Heretofore, the magnetic disk apparatuses that employ the floating magnetic head slider have a pair of rails mounted on laterally opposite ends of the magnetic head slider that face the magnetic disk. Each of the rails has a flat air bearing surface. Each of the rails also has a tapered surface on its air inlet side. An airflow that is produced when the magnetic disk rotates at a high speed impinges upon the air bearing surfaces, causing the magnetic head slider to float to keep the electromagnetic transducer spaced from the surface of the magnetic disk by a stable minute gap.
The CSS floating magnetic head slider assures high floating stability and a minute floating gap (submicrons). However, when the magnetic disk is stopped, the air bearing surfaces of the magnetic head slider are held in contact with the magnetic disk. At the time the magnetic disk apparatus starts and stops operating, the magnetic disk and the air bearing surfaces slide against each other. Therefore, the magnetic disk has, on its recording layer, a protective layer made of a hard material such as carbon or the like and a lubricating layer for reducing friction and wear of the protective film to increase the durability of the magnetic disk. Although the lubricating layer is effective to reduce friction and wear of the protective film, the lubricating layer allows the magnetic disk and the magnetic head slider to stick to each other when the magnetic disk apparatus stops its operation, with the result that the magnetic disk apparatus may not be able to start operating.
In order to solve the problem of sticking between the magnetic head slider and the magnetic disk, it has been proposed to provide a plurality of pads (projections) on the floating surface (the air bearing surfaces) of the magnetic head slider for thereby reducing the area of contact between the magnetic head slider and the surface of the magnetic disk (see Japanese Patent Laid-open No. Hei 8-69674, for example). There is another magnetic head slider in which sticking prevention pads are disposed on a stepped surface lower than the air bearing surfaces, the sticking prevention pads having a height slightly greater than the height of the air bearing surfaces.
The electromagnetic transducer includes a recording coil embedded in an insulating protective film made of Al2O3, for example. For writing data, a voltage modulated by the data is applied to the recording coil, which generates a magnetic signal that is recorded on the magnetic disk. In recent magnetic head drives, the recording coil generates more heat as the data is transferred thereto at a higher rate. When the recording coil generates increased heat, the insulating protective film with the electromagnetic transducer embedded therein is thermally expanded and projects from the floating surface (the air bearing surfaces) of the magnetic head slider. Since the recent magnetic head drives are designed to cause the magnetic head slider to float off the magnetic disk by a smaller gap than ever, if the recording coil significantly projects from the floating surface, then the projecting portion of the insulating protective film tends to contact the magnetic disk with an increased probability, possibly causing a head crash.